‘Candidatus Phytoplasma solani’ strain SA-1 has a highly repetitive genome
M. SERUGA MUSIC (1), S. Hogenhout (2), C. Kuo (3) (1) Department of Biology, Faculty of Science, University of Zagreb, Croatia; (2) Department of Cell and Developmental Biology, John Innes Centre, United Kingdom; (3) Institute of Plant and Microbial Biology, Academia Sinica, Taiwan

Despite being small in size, genomes of phytopathogenic bacteria from the genus ‘Candidatus Phytoplasma’ can be difficult to study due to their repeat-rich nature and the fact that they cannot be grown outside their plant and insect hosts. Nevertheless, genomes of five phytoplasma strains have been completely sequenced and a number of draft assemblies are also available. Among the latter, ‘Ca. P. solani’ possesses one of the largest genomes. It is transmitted by polyphagous cixiid insect vectors and has a wide plant host range. In this study, the genomes of two ‘Ca. P. solani’ strains were sequenced: strain 396 from a field sample of infected grapevine and strain SA-1 originating from grapevine and maintained in periwinkle. Libraries were generated from whole plant samples and sequenced on the Illumina MiSeq platform. After de novo assembly, contigs belonging to the phytoplasma genomes were extracted and analyzed. The sample SA-1 generated a better draft assembly of ~ 590 kb in 39 contigs. This is an improvement compared to two other draft assemblies available for ‘Ca. P. solani’,  comprising 128 contigs and 298 contigs of 574 kb and 545 kb, respectively. Repeat-rich regions were responsible for the incomplete assembly of the SA-1 genome. We hypothesize that these repeats may be associated with high plasticity of the ‘Ca. P. solani’ genome, which in turn promotes a higher rate of molecular evolution for adaptation of this bacterium to various plant and insect hosts.

Abstract Number: P11-377
Session Type: Poster